Evaluation of Imidacloprid Residues in Okra Fruits by LC-MS/MS

Residues of imidacloprid applied as foliar spray at every ten day's interval to control leaf hopper (Amrasca bigutulla bigutulla, Ishida) on okra fruits were determined by LC-MS/MS at three successive pickings following each application at flowering-fruiting stage. Residues were the highest at the first picking after spray and lowest at the third picking and were in the range of 0.10 to 0.16 ug g⁻¹.The residues in fruits at all the pickings following all applications remained below the maximum residue limit of 0.5 μg g⁻¹ for imidacloprid on okra. The farmer's practice of spraying imidacloprid in okra every 10 days at the recommended dose of 0.3 mL L⁻¹ was therefore found to be safe if the produce was harvested at least two days after the previous application of the insecticide. Leaf hopper population was effectively controlled by application of imidacloprid.